Your net worth is your assets (cash, investments, property, etc.) minus any debts (credit cards, students & car loans, mortgages, etc.). Even if you're starting with a negative net worth, keeping track will show you your progress.
Your credit score is a number between 0-800 based on the age and type of credit accounts you have, your ratio of utilized to available credit, and your on-time payment history. Lenders, employers, and landlords look at your credit score as part of their approval process, and a lower score often results in higher interest rates.
Everybody should have some money set aside for emergencies. Even a few hundred dollars can help keep an unexpected expenses from becoming a catastrophe, but most experts recommended saving from $1000 to 6+ months of expenses. Determine what number makes sense for you and start setting aside a little money each month towards your goal.